The present invention relates to a bending tool, and more particularly to a bending tool which is particularly useful for bending of a bendable member along a bending line which divides the bendable member into first and second arm portions.
The bendable members for which the present invention is particularly useful may for example comprise electrical connectors used for providing electrical connection with suitable conductors. Examples of such bendable members are disclosed in U.S. Pat. No. 3,549,786 and in U.S. Application Ser. Nos. 42,356 and 42,441, filed on even date herewith and entitled "Termination Connector" and "Self-Locking Clamp Member," respectively. However, it will be apparent to those skilled in the art that the bending tool of the present invention is also useful with other types of bendable members for other applications.
Typical electrical connectors for which the bending tool of the present invention is particularly useful have generally been of a folded or hinged construction so as to permit their placement over the end or edge of an insulated conductor or conductors of a flat conductor cable. The hinged construction identifies the point about which the closure will take place so that when the connector is installed in place, the first and second arm portions are adapted to overlie one another with the conductor being located therebetween. Such hinged connectors may for example include a plurality of pointed protrusions or teeth, or other devices located on the internal facing sides of the connectors for providing a piercing and/or material displacing action of the insulating material covering and separating the individual conductors in the flat conductor cable (see for example the aforementioned U.S. Pat. No. 3,549,786 and application Ser. Nos. 42,356 and 42,441). This piercing and/or material displacing action typically affords a means of establishing electrical contact between the connector and the conductor. In more recent type electrical connectors, means for locking or affixing the installed connector in its closed configuration may also be provided so that the natural resilient properties of the materials held in compression by the installed connector do not degrade the electrical connection by separating the closed halves of the connector (see for example the aforementioned copending U.S. application Ser. No. 42,441, entitled "Self-Locking Clamp Member"). Still further, provision may be made for securing or terminating the connector to a receiving point, thereby providing means for the transfer of electrical power from the cable to a suitable receptacle (see for example the aforementioned copending U.S. application Ser. No. 42,356, entitled "Termination Connector").
Prior to installation, such electrical connectors have their respective arm portions separated or inclined with respect to one another to allow for the flat conductor cable therebetween. The connectors are then crimped, folded or otherwise bent to install or clamp the connectors in place on the flat conductor cable. Preferably, in the installed condition, the two arm portions will lie both flat and parallel to each other and to the conductor therebetween . This ensures the desired action of any insulation piercing and/or material displacing devices to properly establish electrical contact between the connector and the conductor. Additionally, such an arrangement will minimize forces tending to unbend the connector so as to ensure that the connector will remain installed in place.
As can be appreciated, it is most important for the proper installation of such hinged type connectors that the force used to achieve closure be applied in a manner such that the desired configuration for the connector when installed is achieved. In this regard, it is preferable that a uniform pressure distribution be applied to both sides or arm portions of the connector, (and ideally over the entire flat outside surfaces of the two arm portions) during the closure operation.
Prior art bending tools for bending of such hinged type connectors have generally utilized a toggle mechanism in order to provide high force multiplying characteristics in a compact size so that the tool is comfortably usable with one hand while at the same time providing the high measure of force required for completing a proper closure of hinged type connectors. Two examples of the most commonly used hand tool configurations employing such toggle mechanisms are shown schematically in FIGS. 1 and 2. In both of these FIGS., the open position of the tool (i.e., the position for receiving the hinged type connector before installation) is shown in solid outline while the closed position of the tool (i.e., the position after bending of the connector) is shown in dotted outline.
The tool represented by FIG. 1 is a linear motion type tool 10 having a movable jaw or die member 12 fixably secured to a movable support member 14 which in turn is guided by a guide 16 to move along a straight line path perpendicularly toward a stationary jaw or die member 18 supported by the main tool body 20. A link 22 is pivotally connected at 24 to the end of the movable support member 14 and pivotally connected at 26 to a moving member or handle 28. The handle 28 is pivotally connected at 30 to the tool body 20 so that pivotal movement of the handle 28 about the pivot connection 30 causes the movable support member 14 and jaw 12 fixably supported thereon to move towards the stationary jaw 18 to effect a closing of a connector inserted between the two jaws 12, 18. The toggle mechanism, which comprises link 22 and the end of the handle 28 develops its greatest force only when the included angle between the link 22 and handle 28 approaches 180.degree. (i.e., when the two portions form a staight line).
With such a tool 10, the jaws 12, 18 first contact the connector at its widest point, and unless some provision is made to restrain the connector in the jaw members 12, 18, the connector would have a tendency to "float" between the two jaw members 12, 18 whereby neither arm portion of the connector is fully contacted by the jaws 12, 18. Thus, the force applied by the two jaw members 12, 18 would be concentrated at the ends of the two arm portions of the connector, thereby possibly resulting in a non-uniform closing of the connector about its bending line with the sides or arm portions of the connector being distorted or bowed. Such an improper closure may result in a non-uniform displacement and/or penetration of the conductor insulating material and the possibility of inadequate electrical contact.
In the other type of tool configuration, represented in FIG. 2, a toggle linkage mechanism is again provided which comprises a first link 22' pivotally connected at 24' to a pivotally mounted support arm 14' and at 26' to the end of a handle 28', which handle 28' in turn is pivotally supported at 30' on the tool body 20'. A jaw member 12' for engaging one arm portion of a connector is fixably secured to the end of the pivotal support member l4' so that the jaw member 12' pivots or swings about the fixed pivot point 32 of the support arm 14' in moving between the open position and the closed position. That is, the jaw member 12' is moved towards the stationary jaw or die member 18' on an arc about the fixed pivot point 32 of the support arm 14'.
while this latter configuration provides a more suitable mechanism for proper installation of hinged type connectors, it requires that the fixed pivot point 32 be precisely located in line with the hinged fold. Additionally, it requires that the connector always be properly placed accurately between the jaw or die members 12', 18' so that the hinged fold will always be in line with the fixed pivot point. If this is not achieved, the closure would again start with pressure being exerted only at the widest points of the connector, thus resulting in similar problems as experienced with the tool represented in FIG. 1.
The present invention is directed to an improved bending tool for overcoming these and other disadvantages experienced in the prior art.